ch. 12 Fungi Flashcards
1
Q
Fungi characteristics
A
cell type: eukaryote
cell membrane: sterols present
cell wall: Glucans; mannans; chitin (no peptidoglycan)
spores: sexual and asexual reproductive spores
metabolism: heterotrophic; aerobic, facultatively anaerobic (only a few are anaerobic)
2
Q
vegetative structures
A
-fungal colonies are described as vegetative structures because composed of cells involved in catabolism and growth
3
Q
molds and fleshy fungi structure
A
- thallus= body–consists of long filaments joined together called hyphae.
- hyphae–can grow to immense proportions, from the tips. contain septa
- septa–walls that divided hyphae into distinct, uninucleate cell-like units= septate hyphae
- coenocytic hyphae–no septa. appear as long continuous cells with many nuclei.
- vegetative hypha–obtains nutrients
- reproductive/aerial hypha–produce reproductive spores
4
Q
yeasts
A
- nonfilamentous
- unicellular fungi
- typically spherical or oval shaped
- with oxygen–metabolize carbs to CO2 and H2O
- without oxygen–carbs to ethanol and CO2–fermentation used in alcohol and baking
5
Q
budding yeasts
A
- budding yeasts reproduce via budding; parent cell forms a protuberance, the nucleus divides and one nucleus enters the protuberance, then the protuberance breaks off.
- one yeast cell can produce up to 24 daughter cells via budding
- not all buds detach–they form a short chain of cells called pseudohypha–help invade deeper tissues.
- budding yeasts often divide unevenly
6
Q
fission yeasts
A
-divide evenly to produce 2 new cells
-
7
Q
dimorphic fungi
A
- dimorphism= two forms of growth
- mold or yeast
- mold–produce vegetative and aerial hyphae
- yeast–reproduce via budding
- often pathogenic
8
Q
spores
A
- different from bacterial endospores–help in reproduction rather than protection from environment (bacteria)
- spore type helps to identify different fungi
- formed in sexual and asexual reproduction
- asexual spores–formed by hyphae of one organism; genetically identical to parent.
- sexual spores–result from fusion of nuclei from two opposite mating strains of same species. require two different mating strains so less common; contain genetics from both parents
9
Q
asexual spores (conidiospore)
A
- produced by one fungus through mitosis and subsequent cell division
- NO fusion of nuclei of cells
- 2 types of spores:
1. conidiospore/conidium: unicellular or multicellular spore that is not enclosed in a sac. produced in a chain at the end of a conidiophore (penicillin, aspergillus)
a. arthroconidia–formed by fragmentation of a hypha into a single thick cell (coccidioides)
b. blastoconidia–formed from buds of parent cell (candida albicans, cryptosporidium)
c. chlamydoconidium–thick walled spore from roundin and enlargment within hyphal segment (candida albicans)
10
Q
asexual spores (sporangiospore)
A
- produced by one fungus through mitosis and subsequent cell division
- NO fusion of nuclei of cells
- 2 types of spores:
2. sporangiospore/sporangium: enclosed in a sac called a sporangium at the end of an aerial hypha called a sporangiophore - sporangium can contain hundreds of sporangiospores
- produced by rhizopus
11
Q
sexual spores
A
- results from sexual reproduction.
- 3 phases:
1. plasmogamy: a haploid nucleus of a donor cell (+) penetrates the cytoplasm of a recipient cell (-)
2. karyogamy: the (+) and (-) nuclei fuse to form a diploid zygote nucleus.
3. Meiosis: the diploid nucleus gives rise to haploid nuclei (sexual spores) some of which may be genetic recombinants.
12
Q
nutritional adaptations
A
- fungi grow better at pH5–too acidic for most bacteria
- most molds are anaerobic; most yeasts are facultative anaerobes
- most fungi are resistant to osmotic pressure–can grow in relatively high sugar or salt concentrations
- fungi can grow on substances with low moisture content–often too low for bacteria
- fungi require less nitrogen
- fungi can metabolize complex carbs like lignin (in wood) that most bacteria cant use for nutrients.
13
Q
telemorphs and anamorphs
A
- telemorph: fungi that produce both sexual and asexual spores.
- anamorphs: can only reproduce asexually.
14
Q
fungal diseases
A
- fungal infection = mycosis
- difficult to treat because fungi are related to animals—so cells are similar. If we are targeting fungal cells, it is had to avoid animal cells
-5 groups systemic subcutaneous cutaneous superficial opportunistic
15
Q
systemic mycoses
A
-infections deep within body that can affect many tissues and organs
- usually caused by fungi in soil
- spores transmitted via inhalation so the infections usually begin in lungs and then spread
- not contagious from human to human/animal to animal
ex. histoplasmosis, and coccidiodomycosis
